隐性动物是指由目击者报告或轶事证据暗示其存在，但缺乏确凿证据的动物。 你听到最多的隐性动物是尼斯湖鼻涕虫和大脚兽，但这些动物似乎很可能纯粹是虚构的，它们的骨骼不会在博物馆中看到。 其他动物曾经被认为是隐性动物，但现在已知存在。 这些动物包括巨型乌贼、鸭嘴兽、霍加狓、灰熊和北极熊的混血儿以及科莫多龙。 类似的情况包括被认为已经灭绝的动物后来被发现存在，例如coelacanth（一种鱼类），或者在神话中存在而后来发现类似化石的动物，例如被认为只在13000年前灭绝了的 "霍比人" ，佛罗伦萨人。

The giant squid is quite possibly the most famous cryptid that turned out to exist. Giant squids have been mentioned in natural history books since the time of the ancients, and both Aristotle and Pliny the Elder described the beast, which was said to have tentacles up to 9 m (30 ft) long. Tales of giant squid had long been shared among mariners, but no conclusive evidence was produced until 1861, when the French gunboat Alecton encountered a giant squid and tried to capture it, coming away with nothing but a tentacle. But the tentacle was enough for the cryptid to arouse the interest of the scientific community, which gave it the scientific designation Architeuthis, which means "great squid" in Latin. Throughout the late 1800s, many giant squids washed up on shores in Newfoundland and New Zealand, and only recently, in 2004, a giant squid was filmed in its natural habitat, miles beneath the surface of the ocean.

另一种曾经被认为是神秘动物的动物，其存在已被证实，那就是霍加狓，这种动物似乎有斑马的腿，身体覆盖着红棕色的毛发，舌头黑得像长颈鹿。 生活在刚果东北部茂密的伊图里雨林的欧洲人只通过当地人的故事听说过霍加狓，并因其难以捉摸而被称为 "非洲独角兽"。 1902年，英国人哈里-约翰斯顿爵士偶然发现了一个头骨和一块条纹皮肤，科学家用它将这种动物（正确）列为长颈鹿的一个亲戚。 第一个活标本直到1918年才被带到欧洲。

Another of the famous historic cryptids is the platypus. This Australian mammal is a monotreme, a type of mammals that were once abundant (in Australia) but today only includes the platypus and echidna. The platypus has been described as "duck-billed, beaver-tailed, and otter-footed." Instead of giving birth to live young like practically every other mammal, it lays eggs. It is also has some of the most excruciating venom of any animal in the world, injecting it into attackers with a spur on its hind leg. In 1789, English sailor Captain John Hunter sent a platypus pelt back to England as proof of the animal's existence. Thinking that the pelt was a hoax by taxidermists, scientists greatly doubted its veracity at first. But over the course of two years, encouraged by further eyewitness reports, scientists began to accept the animal as biological reality. They even cut up the first pelt to check it for signs of stitches.